Dresser RCS User manual

r
ROOTS
$2.00
INSTRUCTIONS
ROTARY LOBE BLOWERS
CONTENTS
NUMBERS IN ( ) ARE METRIC EQUIVALENTS
INFORMATION SUMMARY ........... This page
Receiving
... Installing ... Operating
OPERATING CHARACTERiSTiCS ............. 2
Description
... Control ... Protection
OPERATING LIMITATIONS .................. 2
Pressure
... Temperature ... Speed
INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . .. 3
Mounting
... Aligning ... Piping
LUBRICATION ............................. 6
Oil System ... Sealing ... Servicing
OPERATION ............................... 6
Starting
... Checking ... Running
TROUBLE SHOOTING
....................... 7
Capacity
... Power ... Heating
SAFETY PREACUTIONS. . . . . . . . . . . . . . . . . . . .. 8
Physical
... Operating ... General
MAINTENANCE/REPLACEMENTS
............ 8
Servicing
... Repairs ... Clearances
PARTS DRAWiNGS
......................... 13
DISTRIBUTORS ............................ 20
DO THESE THINGS .... To Get The Most From Your Roots Blower
IICheck shipment for damage in transit. After filing
claim with carrier, notify nearest Sales Office or factory.
ElUnpack shipment carefully and check contents
against Packing List. Notify Sales Office or factory if a
shortage appears.
BlStore in a clean, dry location until ready for installa~
tion, if possible. Lift by methods discussed under IN-
sTALLATION to avoid straining or distorting the equip-
ment. Keep covers on all openings. Protect against
weather
and corrosion if outdoor storage is necessary.
LIMITATIONS and INSTALLATION sec-
tions in this manual and plan the complete installation. If
supervision by a Service Engineer is needed, contact the
nearest Dresser Parts and Service Center at least two
weeks in advance
and confirm by your purchase order.
Standard charges will be made.
IDProvide for adequate safeguards against accidents to
persons working on or near equipment during both in-
stallation and operation. See PRECAUTIONS.
iii Install all equipment correctly. Foundation design
must be adequate and piping carefully done. Use recom-
mended accessories for operating protection.
IiIMake sure both driving and driven equipment is cor-
rectly lubricated before start-up. See LUBRICATION.
'::1Read starting check points under OPERATION. Run
equipment briefly to check for obvious faults, and make
corrections. Follow with a trial
run under normal
operating conditions.
mIn the event of trouble during installation or opera-
tion of a new unit, do not attempt repairs. Notify nearest
Sales Office or factory, giving all nameplate information
plus
an outline of operating conditions and a description
of
the trouble.
EUnits out of warranty may be repaired or adjusted by
the owner. It is recommended that suchwork belimited to
the operations described in this manual, using Factory
Parts. Good inspection and maintenance practices should
reduce
the need for repairs. See Distributor List on last
page for parts and service after warranty period.
NOTE -Information In this manual is correct as of the date of publication.The Manufacturer reserves the right to make design or material changes without notice, and
without obligation to make similar changes on equipment of prior manufacture.
Bulletin IRB-115-387

OPERATING CHARACTERISTICS
Roots RCS blowers, as covered in this manual, are
available in basic frame size of 4Y2 inch gear diameter.
Within this frame size are two case lengths, selected to
produce reasonable steps in blower carJacity ratings. All
units are designated as air blowers, and may be used for
handling air in either pressure or vacuum service. They
are unsuitable for handling gases because shaft seals are
not designed to prevent leakage to atmosphere.
The basic Roots rotary lobe blower is a positive
displacement
type unit, whose pumping capacity is deter-
mined
by size, operating speed and pressure conditions. It
employs two double-lobe impellers mounted on parallel
shafts and rotating in opposite directions within a
cylinderclosed
at the ends by headplates. As the impellers
rotate, air is drawn into one side of the cylinder and forced
out the opposite side against the pressure existing there.
The pressure developed, therefore, depends on the
resistance of the discharge system.
Effective sealing of the blower inlet area from the
discharge area is accomplished by use of very small
operating clearances. Resulting absence of moving con-
tacts eliminates the need for any internal lubrication.
Clearance
between the impellers during rotation are main-
tained by a pair of accurately machined timing gears,
mounted on the two shafts extended outside the blower
casing.
Operation of the rotary lobe blower is illustrated in
FIGURE 1, where air flow is right to left from inlet to
discharge with the lower impeller rotating clockwise. In
Position 1 it is delivering a known volume (A) to the
discharge, while space (B) between the upper impeller and
cylinder wall is being filled. Counterclockwise rotation of
this impeller then traps equal volume (B) in Position 2,
and further rotation delivers it to the discharge in Posi-
tion 3. At the same time, another similar volume is form-
ing under the lower impeller, and will be discharged when
rotation reaches Position 1 again.
One complete revolution of the driving shaft alter-
nately traps four equal and known volumes of air (two by
each impeller) and pushes them through to the discharge.
The pumping capacity of a lobe blower operating at a con-
stant speed therefore remains relatively independent of
reasonable inlet or discharge pressure variations. To
change capacity, it is necessary either to change speed or
rotation or vent some of the air.
No
attempt should ever be made to control capacity
by means ofa throttle valve in the intake or dischargepip-
ing. This will not only increase the power load on the
driver, but can also overload and seriously damage the
blower. If a possibility does exist that flow to the blower
inlet may be cut off during normal operation of a process,
then an adequate vacuum relief valve must be installed
near the blower. A pressure type relief valve in the
discharge line near the blower is required for protection
against cut-off or blocking in this line. See Figure 2.
When a belt drive is employed, blower speed can
usually be adjusted to obtain desired capacity by dhang-
ing the diameter of one or both sheaves. In a direct
coupled
arrangement a variable speed motor or transmis-
sion is required, or excess air
may be blown off through a
manually controlled unloading valve and silencer. If
returned to the blower inlet, the air must be cooled to
100 OF (38°C) through a by-pass arrangement to maintain
acceptable blower temperatures.
Before making any change in blower capacity, or
operating conditions,
contact the nearest Sales Office for
specific information
applying to your particular blower.
In all cases, operating conditions must be maintained
within the approved range of pressures, temperatures and
speeds as stated under LIMITATIONS. Also, the blower
must not be used to handle air containing liquids or solids.
Serious damage to the rotating parts will result.
OPERATING LIMITATIONS
To permit continued satisfactory performance, a
Roots RCS blower must be operated within certain ap-
proved limiting conditions. The Manufacturer's warranty
is, of course, also contingent on such operation.
Maximum limits for pressure, temperatures and
speed are specified in Table 1 for RCS blowers. These
limits
apply to all blowers of normal construction, having
operating clearances as listed in Table 5, when operated
•
POSITION 1 POSITION 2 POSITION 3
K ~207'J
Figure 1 :- Flow Through ReS Blower
2

l,
under standard atmospheric conditions. Do not exceed any
one of these limits.
Example: The listed maximum allowable temperature
rise (increase in ail' temperature between inlet and
discharge) for any particular blower may occur well before
its maximum pressure or vacuum rating is reached. This
can easily occur at high altitude or at very low speed.
Temperature rise then is the
limiting condition. In other
words, the operating limit is always determinedby the max-
imum rating reached first. It can be anyone of the three:
pressure, temperature or speed.
Be sure to
arrange connections or taps for thermometers
and mercury type pressure or vacuum gauges at or neal'
the inlet and discharge connections of the blower. These
along with a good tachometer, will enable periodic checks
of
operating conditions to be made easily.
PRESSURE-On pressure service; the pressure rise
(between blower inlet and discharge) must not exceed the
figure listed for the specific blower frame size concerned.
Also,
in any system where the blower inlet is at a positive
pressure above atmosphere, the discharge pressure must
never exceed 25 PSI (172 kPa) gauge regardless of blower
size.
On vacuum service, with the discharge going to at-
mospheric
pressure, the inlet suction or vacuum must not
be greater than values listed for the specific frame size.
TEMPERATURE-RCS blower frame sizes are ap-
proved only for
installations where the following tempera-
ture limitations can be maintained in service.
A. Measured temperature rise must not exceed listed values
when the inlet is at ambient temperature. Ambient is
considered as the general temperature of the space
around the blower. This is not outdoor temperature
unless the blower is installed outdoors.
B. If inlet temperature is higher than ambient, the listed
allowable temperature rise values must be reduced by
%of the difference between the actual measured inlet
temperature and the ambient temperature.
C. An average temperature between inlet and discharge up
to 250°F. (121°C).
SPEED RANGE-RCS blowers may be operated at
speeds up to the maximum listed for the sizes. They may
be direct coupled to suitable constant speed drivers if
pressure/temperature conditions are also within limits. At
low speeds, excessive temperature rise may be the limiting
factor as noted in the preceding example.
Table 1-Maximum Allowable Operating Conditions
Frame Speed
Press. Rise Inlet Vac. Temp. Rise
Size RPM
PSI
(kPa)
In.
(kPa)
FO Co
Hg.
404 3820
15
(104)
15
(50)
275
(153)
406 3820
15
(104)
15
(50)
275
(153)
409 '3820
15
(104)
15
(50)
275
(153)
412 3820
15
(104)
15
(50)
275
(153)
418 3820
15
(104)
15
(50)
275
(153)
616
2860 10
(69)
15
(50)
230
(128)
624 2820
10
(69)
15
(50)
230
(128)
INSTALLATION
Roots RCS blowers are internally and externally
treated after factory assembly to protect against normal
atmospheric corrosion before installation. The maximum
3
period of internal protection is considered to be one year
under average conditions, if closing plugs or seals are not
removed. Protection against chemical or salt water at-
mosphere is not provided. Avoid opening the blower until
ready to start installation, as protection will be lost quick-
ly by evaporation. .
If there is to be an extended period between installa-
tion and start up, the following steps should be taken to
insure corrosion protection:
1. Coat internals of cylinder, gearbox and drive
end bearing reservoir with Motorstor or
equivalent. Repeat once a year or as conditions
may require. Motorstor is oil soluble and does not
have to be removed before lubricating. If desired,
Motorstor may be removed from within the
cylinder shortly before start up by spraying a fine
mist of petroleum solvent through the blower
while
it is running at a slow speed with open inlet
and discharge, or it can remain in the blower if it is
not harmful to the operation of the connected
system.
Motorstor is a product of Daubert
Chemical Co., 2000 Spring Rd., Oak Brook, Ill.
60521.
2. Paint shaft extension, inlet and discharge flanges,
and all other exposed surfaces with Nox-Rust
X-145'or equivalent.
3. Seal inlet, discharge, and vent openings. It is not
recommended that the unit be set in place, piped to
the system, and allowed to remain idle for extend-
ed periods.
If any part is left open to the at-
mosphere,
the Motorstor vapor will escape and
lose its effectiveness.
4. Units are not to be subjected to excessive vibra-
tion
during storage. If stored outdoors, provide
coverage
such as a tarpaulin or lean-to.
5. Rotate drive shaft three or four revolutions every
two weeks.
6. Prior to start up, remove flange covers on both in-
let and discharge and inspect internals to insure
absence of rust. Check all internal clearances. Also,
at this time, remove gearbox and drive end bearing
cover and inspect gear teeth and bearings for rust.
Because of the completely enclosed blower design,
location of
the installation is generally not a critical mat-
ter. A clean,
dry and protected indoor location is pre-
ferred. However,
an outdoor or wet location will normally
give
satisfactory service. Important requirements are
that the correct grade of lubricating oil be provided for ex-
pected temperatures, and that the blower be located so
that routine checking and servicing can be handled
conveniently
after installation. Effect of the location on
driver and accessory equipment must also be considered.
Supervision of the installation by a Factory Service
Engineer is not usually required for these blowers.
Workmen with experience in installing light-medium
weight machinery should be able to produce satisfactory
results. Handling of the equipment needs to be ac-
complished
with care, and in compliance and safe prac-
tices. Blower
mounting must be solid, without strain or
twist, and air piping must be clean, accurately aligned and
properly connected.

Two methods may be used to handle a blower without
base. One is to use eyebolts screwed into the top of the
headplates. Test them first for tightness and fractures by
tapping with a hammer. In lifting, keep the direction of
cable pull
on these bolts as nearly vertical as possible. If
eyebolts are not available, lifting slings may be passed
under the cylinder adjacent to the headplates. Either
method prevents strain being placed on the extended
drive shaft.
When blower is furnished mounted on a baseplate,
with or without a driver, use of lifting slings passing
under the base flanges is required. Arrange these slings so
that no strains are placed on the blower casing or mount-
ing feet, or on any mounted accessory equipment. DO
NOT use
the eyebolts in the top of the headplates.
Before
starting the installation, remove plugs, covers
or seals from blower inlet
and discharge connections and
inspect the interior completely for dirt or foreign material.
If cleaning is required, finish by washing the cylinder,
headplates and impeller thoroughly with a petroleum sol-
vent such as DuPont Triclene D. After this, turn the drive
shaft by hand to make sure that the impellers turn freely
at all points. Anti-rust compound on the connection
flanges
and drive shaft extension may also be removed at
this time with the same solvent. Then cover the flanges
again to keep out dirt until ready to connect the air pip-
ing. Washing out is not required if the interior is found to
be clean. The corrosion inhibitor used will vaporize and
disappear during operation.
Care, plus consideration of all possible problems, will
pay dividends when arranging the blower mounting. This
is especially true when the blower is a "bare" unit, fur-
nished without a baseplate. The convenient procedure
may be to mount such a unit directly on a floor or small
concrete
pad, but this generally produces least satisfac-
tory results. It definitely causes the most problems in
leveling
and alignment.
Direct use of structural framing members is also not a
recommended mounting.
If unavoidable, the members
must be rigidly reinforced when part of a building, and
spring type mountings should not be used. Noise
transmission can usually be reduced by use of a cork in-
sulating pad 1 to 2 inches (25 to 50 mm) thick. The pad
should be supported by a full steel plate attached to the
structure, with a rigid concrete slab laid on top of the cork
to carry the blower and driver.
For a blower without base, it is recommended that a
well anchored
and carefully leveled steel or cast iron
mounting plate be provided at the installation point. The
plate should be about 1 inch (25 mm) thick, with its top
surface machined flat, and large enough to provide level-
ing areas at one side and one end after the blower is
mounted.
It should have properly sized studs or tapped
holes located to match the blower foot drilling. As an
alternative, smaller plates at each end of the blower may
be used. This is more complicated usually makes leveling
more difficult,
and can produce twist or strains in the
blower. Use of a high quality machinist's level is impor-
tant.
With the mounting plate in place and leveled, set the
blower on it without bolting and check for rocking. If it is
4
not solid, determine the total thickness of shims required
under one foot to stop the rocking. Place halfof this under
each of the diagonally-opposite short feet, and tighten the
mounting studs or screws. Rotate the drive shaft to make
sure the impellers still turn freely. If the blower is to be
direct coupled to a driving motor, consider the height of
the motor shaft and the necessity for it to be aligned very
accurately with the blower shaft. Best arrangement is for
the blower to be bolted directly to the mounting plate
while the driver is on shims of at least 1/8 inch (3 mm)
thickness.
This allows adjustment of motor position in
final
shaft alignment by varying the shim thicknesses.
When blower and driver have been factory mounted
on a common baseplate, the assembly will have been pro-
perly aligned and is to be treated as a unit for leveliIJ.g pur-
poses. Satisfactory installation can be obtained by setting
the baseplate on a concrete slab that is rigid and free of
vibration,
and leveling the top of the base carefully in two
directions so
that it is free of twist. The slab must be pro-
vided with suitable anchor bolts. The use of grouting
under and partly inside the base, after it has been careful-
ly leveled by shimming, is recommended.
It is possible for a base-mounted assembly to become
twisted during shipment, thus disturbing the original
alignment.
For this reason, make the following checks
after the base has been leveled and bolted down. Discon-
nect the drive and rotate the blower shaft by hand. It
should turn freely at all points. Loosen the blower foot
hold-down screws
and determine whether all feet are even-
ly in contact with the base. If not, insert shims as required
and again check for free impeller rotation. Finally, if
blower is direct coupled to the driver, check shaft and
coupling alignment carefully and make any necessary cor-
rections.
In planning the installation, and before setting the
blower, consider how piping arrangements are dictated by
the blower design and assembly. RCS blowers have rever-
sible rotation.
Standard arrangement on vertical units has the drive
shaft at the top. Horizontal units' standard arrangement
has the drive shaft at the left.
When a blower is DIRECT COUPLED to its driver,
the driver RPM must be selected or governed so as not to
exceed
the maximum speed rating of the blower. Refer to
LIMITATIONS for allowable speeds for various blower
sizes. A flexible
type coupling should always be used to
connect the driver and blower shafts.
Coupling halves must be accurately aligned, and a
sufficient
gap between shaft ends provided so that side
strains and end thrust on either shaft are avoided or
minimized. This will require considerable care in the
mounting of the driver. The two shafts must be in as near
perfect alignment in all directions as possible, and the gap
must be established with the motor armature on its elec-
trical center if end play exists.
The following requirements for a good installation are
recommended. Coupling halves
must be, fitted to the two
shafts so that only light tapping is required to install
them.
Maximum deviation in offset alignment of the
shafts should not exceed .005" (.13 mm) total indicator
reading,
taken on the two coupling hubs. Maximum devia-

tion from parallel of the inside coupling faces should not
exceed .001" (.03 mm) when checked at six points around
the coupling.
When a blower is
BELT DRIVEN, the proper selec-
tion of sheave diameters will result in the required blower
speed. This flexibility can lead to operating temperature
problems caused
by blower speed being too low. Make
sure
the drive speed selected is within the allowable range
for
the specific blower size, as specified under LIMITA-
TIONS.
Belt drive arrangements usually employ two or more
V-belts running
in grooved sheaves. Installation of the
driver is less critical than for direct coupling, but its shaft
must be level and parallel with the blower shaft. The
driver should be mounted on
the inlet side of a vertical
blower (horizontal piping)
and on tlie side nearest to the
shaft on a horizontal blower. The driver must also be
mounted on
an adjustable base to permit installig, ad-
justing and removing the V-belts. To position the driver
correctly,
both sheaves need to bemounted on their shafts
and the nominal shaft center distance known for the belt
lengths to
be used.
Install the blower sheave so that its inner hub face is
not more than Ya inch (.3 mm) from the drive end cover.
The
shaft fit should be such that the sheave can be work-
ed into place by hand or by very light tapping. A tight or
driving fit can damage a bearing,
and may cause internal
blower damage
by forcing the impeller out of its normal
operating position. A loose fit
or wobbly sheave will cause
vibration,
and may result in shaft breakage. "
The driver sheave should also be mounted as close to
its bearing as possible, and again should fit the shaft cor-
rectly. Position the driver on its adjustable base so that %
of the total movement is available in the direction away
from
the blower, and mount the assembly so that the face
of
the sheave is accurately in line with the blower sheave.
This position minimizes belt wear,
and allows sufficient
adjustment for both installing and tightening the belts.
After belts are installed,
adjust their tension in accor-
dance with the manufacturer's instructions. However, on-
ly enough tension should be applied to prevent slippage
when
the blower is operating under load. Excessive
tightening can lead to early bearing failures.
In the absence of belt manufacturer's instructions for
tensioning,
the following procedure may be used.
1. With the belts loose, pull the slack on all of them to
the bottom side of the drive.
2. Adjust motor position to tighten belts until they
appear to be seating in the sheave grooves.
3. Thump the belts with your fist. If they feel dead,
tighten them more until they vibrate and feel
springy when struck.
4. Run-in the drive for a short period, after preparing
the blower as instructed in a following paragraph.
While running
adjust until only a very slight bow
appears in
the slack side of the belts.
5. Stop the motor and compare the tensions of the in-
dividual belts by pressing down firmly with one
hand on the top surface. It should be possible to
deflect each beltonly to
the point where its top sur-
face is even with the bottom of the other
underdeflected belts.
5
6. A new set of belts should be first tensioned about
Va greater than normal to allow for stretch and
wear-in. Before
putting the drive into normal
operation, increase
the tension as obtained above
by a small amount. Recheck after each 8 hour
operating period during
the first 50 hours and, ad-
just as necessary.
Before operating
the drive under power to check in-
itial belt tension, first remove covers from the blower con-
nections. Make sure the interior is still clean, then rotate
the shaft by hand. Place a coarse screen over the inlet con-
nection to prevent anything being sucked into the blower
while
it is operating, and avoid standing in line with the
discharge opening. Put oil in the sumps per instructions
under LUBRICATION.
Before connecting PIPING, remove any remaining
anti-rust compound from blower connections. Pipe used
should be no smaller
than these connections, and clean,
new piping throughout is strongly recommended.
In addi-
tion, make sure it is free of dirt, scale, cuttings, weld
beads, or foreign materials of
any kind. To further guard
against damage to the blower, especially when an inlet
filter is
not used, install a substantial screen of 16 mesh
backed with hardware cloth
at or near the inlet connec-
tions. Make provisions to clean this screen of collected
debris after a few hours' operation.
It should be removed
when
its usefulness has ended, as the wire will eventually
deteriorate
and small pieces going into the blower may
cause serious damage.
Pipe flanges or male
threads must meet the blower
connections accurately
and squarely. DO NOT attempt to
correct misalignment by springing or cramping the pipe.
In most cases this will distort the blower casing and cause
impeller rubbing.
In severe cases it can prevent operation
or
result in a broken drive shaft. For similar reasons, pip-
ing should be supported near the blower to eliminate dead
weight strains. Also, if pipe expansion is likely to occur
from temperature change, installation of flexible connec-
tors or expansion joints is advisable.
Figure 2 represents
in diagram form a blower installa-
tion with all accessory items that might be required under
various operating conditions.
Inlet piping should be com-
pletely free of valves or restrictions. When a shut-off
valve (not shown)
cannot be avoided, make sure a full size
vacuum relief is installed near
the blower inlet. This will
protect against blower overload caused by accidental clos-
ing.
CHECK I
VALVEJ
~
BACK-PRESSURE SILENCERS MUST BE MOUNTED
REGULATOR OR WITHIN ONE PIPE DIAMETER
PRESSURE ReliEF OF BLOWER FlANGE.
VALVE INLET FILTER ~
~MANUAL UNLOADING
~-i----~Cl VALVE
INLET SILENCER \
THERMOMETERS &
r PRESSURE GAUGES"
Figure 2 - Installation With Accessories

Ii
ii:
i
Need for an inlet silencer will depend on blower speed
and pressure, as well as sound-level requirements in the
general surroundings. An inlet filter is normally recom-
mended, especially in dusty or sandy locations, for blower
protection. A discharge silencer is also normally sug-
gested for RCS blowers. Specific recommendations on
silencing can be obtained from the nearest Sales Office.
Discharge piping requires, a pressure relief valve,
and should include a manual unloading valve to permit
starting the blower under no-load conditions. Reliable
pressure/vacuum gauges and good thermometers at both
inlet and discharge are recommended to allow making the
important checks on blower operating conditions. The
back-pressure regulator shown in Figure 2 is useful main-
ly when volume demands vary while thE) blower operates
at constant output. If demand is constant, but somewhat
lower than the blower output, excess may be blown off
through the manual unloading valve.
In multiple blower installations where two or more
units operate with a common header, use of check valve is
necessary. These should be ofa direct acting or free swing-
ing type, with one valve located in each line between the
blower and header. Properly installed, they will protect
against damage from reverse rotation caused by air and
material back-flow through an idle blower.
After piping is completed, and before applying power,
rotate the drive shaft by hand again. If it does not move
with uniform freedom, look for uneven mounting, piping
strain, excessive belt tension or coupling misalignment.
DO NOT operate the blower at this time unless it has been
lubricated per instructions. Read LUBRICATION sec-
tion.
LUBRICATION
A very simple lubrication system is employed in RCS
blowers. All friction parts -gears, bearings and oil seals
-are lubricated by the action of oil slingers which dip in-
to the main oil sumps causing oil to splash directly on
gears and bearings and also to fill the small reservoirs
above
the bearings. From these, oil flows, by gravity,
through the bearings and to the oil seals. A drain port is
provided below each
bearing to prevent an excessive
amount ofoil in the bearings. Refer to assembly drawings,
Figures 6 & 7. Entrance of lubricating oil into the blower
air chamber is prevented by the use of double shaft seal-
ing. Lip type seals, located inboard of the bearings in each
headplate, effectively
retain oil within the sumps. Any
small leakage that may occur, should the seals wear,
passes into a cavity in each headplate that is vented and
drained downward. In addition, sealing rings are provided
on both shafts where they pass through the inner walls of
the headplates. These serve to reduce air leakage from or
into
the air chamber and also minimize oil carryover into
the air chamber. They are not sufficiently effective to
enable the blower to handle gases, however.
Oil sumps on each each end of the blower are filled by
removing top plugs, Item (22), and filling until oil reaches
the middle of the oil level gauge, Item (45). See Figure 3.
Filling the sumps should be accomplished with the
blower not operating, in order to obtain the correct oil
6
MAXIMUM ----+1
oPfRAilNG
LEVEL
MI HIM UM ----+I-'"
Figure 3 - Oil Level Gauge
level. Approximate oil quantities required for blowers of
the various configurations are listed in Table 3. Do not
overfill. A good grade of industrial type non-detergent,
anti-foaming,
rust inhibiting oil should be used.
The level should never be allowed to fall below the oil
level
gauge ring when the blower is not operating. It may
rise on the gauge during operation, to an extent depend-
ing somewhat on oil temperture and blower speed, but it
should not be permitted to rise above the oil level gauge
ring.
During the first week of operation, check the oil levels
in the oil sumps about once a day, and watch for leaks.
Replenish as necessary. Oil
should be changed after initial
100 hours of operation. Thereafter, change periods of about
500 hours may be considered normal. In draining the sumps,
remove plugs (22) at the bottom.
Ambient Viscosity
Approximate
Series
SSU At tOO°F. (37.8°C) SAE
No.
Above 90°F. (32°C) 1000-1200
50
32-90o F. (0-32°C) 700-1000 40
0-32°F. (-18-00
C)
500-700 30
Table 2 - Recommended Oil Grades
Gearbox
Drive End
Fl. Oz. (Liters)
Fl. Oz. (Liters)
50
(1.48) 30 (.089)
30 (.089)
18
(0.53)
96 (2.84) 64 (1.89)
64 (1.89) 32 (0.95)
Table 3 - Oil Sump Capacities
OPERATION
Before operating a blower under power for the first
time, recheck the unit and the installation thoroughly to
reduce the likelihood of avoidable troubles. Use the follow-
ing procedure list as a guide, but consider any other
special conditions in the installation.
1. Be certain that no bolts, tools, rags or dirt have been
left
in the blower air chamber.
2. Be certain that inlet piping is free of any debris. If an
outdoor intake witout filter is used, be sure the opening
is located so
it cannot pick up dirt and is protected by a
strong screen or grille. Use of the temporary protective
screen
at the blower as described under INST ALLA-
TION is strongly recommended.
3. Recheck blower leveling, drive alignment and
tightness of all mounting bolts if installation is not re-
cent. If belt drive is used, adjust belt tension correctly.

(
4. Turn drive shaft by hand to make sure impellers still
rotate without bumping or rubbing at any point.
5. Make sure oil levels in the main oil sumps are correct.
6. Check
lubrication of driver. If it is an electric motor, be
sure that power is available and that electrical overload
devices
are installed and workable.
7. Open the manual unloading valve in the discharge air
line. If a valve is in the inlet piping, be sure it is open.
8.
Bump blower a few revolutions with driver to check
that direction of rotation agrees with arrow near
blower shaft, and that both units coast freely to a stop.
After the preceding points are cleared, blower is ready
for trial operation under "no-load" conditions as set up
under Item 7. The following procedure is suggested to
cover this initial operation test period.
a.
Start blower, let it accelerate to full speed, then shut
off. Listen for knocking sounds, both with power on
and as speed slows down.
b.
Repeat above, but let blower run 2 or 3 minutes. Check
for noises, and vibrations of .005 in. (.13 rum) or
greater.
c. Operate blower for about 10 minutes unloaded. Check
oil levels. Feel cylinder and headplate surfaces for
development of spots too hot to touch, indicating im-
peller rubs. Be aware of any noticeable increase in
vibration.
Assuming that all trials have been satisfactory, or
that necessary corrections have been made, the blower
should now
have a final check run of at least one hour
under normal operating conditions. After blower is
TROUBLE SHOOTING CHECKLIST
TROUBLE
No Air Flow
Low capacity
Excessive Power
Overheating of
Bearings or Gears
Vibration
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
POSSIBLE CAUSE
Speed too low
Wrong rotation
Obstruction in piping
Speed too low
Excessive pressure
Obstruction in piping
Excessive slip
Speed too
high
Pressure too high
Impellers rubbing
Inadequate lubrication
Excessive lubrication
Excessive pressure
Coupling misalignment
Excessive belt tension
Misalignment
Impellers rubbing
Worn bearings/gears
Unbalanced or rubbing
impellers
Driver or blower loose
Piping resonances
7
REMEDY
Check by tachometer and compare with speed
shown on Roots Order Acknowledgement.
Compare actual rotation with Figure 1 and ar-
row on blower. Compare driver if wrong.
Check piping, screen, valves, silencer, to assure
an open flow path.
See item 1. If belt drive, check for slippage and
readjust tension.
Check inlet vacuum and discharge pressure,
and compare these figures with specified
operating conditions on Order.
See
item 3.
Check inside of casing for worn or eroded sur-
faces causing excessive clearances.
Check speed and compare with Roots Order
Acknowledgement.
See
item 5.
Inspect outside of cylinder and headplates for
high temperatures areas, then check for im-
peller contacts at these points. Correct blower
mounting, drive alignment.
Restore correct oil levels in main oil sumps.
Check oil level. If incorrect, drain and refill with
clean oil of recommended grade.
See
item 5.
Check carefully. Realign if questionable.
Readjust for correct tension.
See
item 14.
See
item 10.
Check
gear backlash and condition of bearings.
If lateral rotor play exceeds .0lD in. (.25 rum)
replace
gears and bearings.
Scale
or process material may build up on cas-
ing and impellers, or inside impellers. Remove
build-up
to restore original clearances and im-
peller balance.
Tighten mounting bolts securely.
Determine whether standing wave pressure
pulsations are present in the piping. Refer to
Sales Office.

restarted, gradually close the discharge unloading valve
to apply working pressure. At this point it is recommend-
ed that a good pressure gauge or manometer be connected
into the discharge line if not already provided, and that
thermometers be in both inlet and discharge lines.
Readings from these instruments will show whether
pressure or temperature ratings of the blower are being
exceeded.
During the final run, check operating conditions fre-
quently and observe the oil levels at reasonable intervals.
If excessive noise or local heating develops, shut down im-
mediately and determine the cause. If either pressure rise
or temperature rise across the blower exceeds the limit
specified in this manual,
shut down and investigate condi-
tions in the piping system or in the process to which air is
being supplied. Refer to the TROUBL'E SHOOTING
CHECKLIST for suggestions on various problems that
may appear.
The blower should now be ready for continuous duty
operation at full load. During the first few days make
periodic checks to determine whether all conditions re-
main steady, or at least acceptable. This may be par-
ticularly important if the blower is supplying air to a pro-
cess system where conditions can vary. At the first oppor-
tunity, stop the blower and clean the temporary inlet pro-
tective screen. If no appreciable amount of debris has col-
lected, the screen may be removed. See comments under
INSTALLATION. At this same time, verify leveling,
coupling alignment or belt tension, and mounting bolt
tightness.
Should operating experience prove that blower
capacity is a little too high for the actual air requirements,
a small excess may be blown off continuously through the
manual unloading or vent valve. Never rely on the
pressure relief valve as an automatic vent. Such use may
cause the discharge pressure to become excessive, and can
also result in failure of the valve itself. If blower capacity
appears to be too low, refer to the TROUBLE
SHOOTING CHECKLIST first. If no help is found there
it may be possible to increase the blower speed. Before at-
tempting this change, contact the nearest Sales Office for
recommendations. Be prepared to furnish data on actual
air requirements and operating pressure/temperature con-
ditions.
SAFETY PRECAUTIONS·
For equipment covered specifically or indirectly in
this instruction book, it is important that all personnel
observe safety precautions to minimize the chances of in-
jury. Among many considerations, the following should
particularly be noted:
II1II Blower casing and associated piping or accessories
may become hot enough to cause major skin burns on
contact.
II1II Internal and external rotating parts of the blower and
driving equipment can produce serious physical in-
juries. Do not reach into any opening in the blower
while it is operating, or while subject to accidental
starting. Cover external moving parts with adequate
guards.
8
II1II Disconnect power before doing any work, and avoid
by-passing or rendering inoperative any safety or pro-
tective devices.
II1II If blower is operated with piping disconnected, place a
strong coarse screen over the inlet and avoid standing
in the discharge air stream.
II1II Stay clear of open inlet piping (suction area) of
pressure blowers, and the open discharge blast from
vacuum blowers.
II1II Stay clear of the blast from pressure relief valves and
the suction area of vacuum relief valves.
II1II Avoid extended exposure in close proximity to
machinery which exceeds safe noise levels.
II1II Use proper care and good procedures in handling, lift-
ing, installing, operating and maintaining the equip-
ment. \
II1II Casing pressure must not exceed 25 PSI (172 kPa)
gauge. Do not pressurize vented cavities from an ex-
ternal source, nor restrict the vents.
II1II Do not use air bl9wers on explosive or hazardous
gases.
II1II Other potential hazards to safety may also be
associated with operation of this equipment. All per-
sonnel working in or passing through the area should
be warned by signs and trained to exercise adequate
general safety precautions.
MAINTENANCE & REPLACEMENTS
A good program of inspection and maintenance ser-
vicing followed consistently, is the most reliable method
of minimizing repairs to a blower. A simple record of ser-
vices and dates will help keep this work on regular
schedule. Basic service needs are lubrication, checking for
hot spots or increase in vibration and noise, and the recor-
ding of operating pressures and temperatures. Above all,
a blower
must be operated within its specified rating
limits to obtain satisfactory service life.
A newly installed blower should be checked frequent-
ly
during the first month of full-time operation. Attention
thereafter may be less frequent, depending on what the
early checks have shown. Lubrication is normally the
most important consideration. Unless operating condi-
tions are unusually severe, a weekly check of oil levels in
the gearbox and bearing reservoirs, with addition of oil as
required, should be sufficient. Complete oil changes
should be made at intervals of 250 operating hours, or
more frequently if oil condition becomes poor.
Driver lubrication practices should be in accordance
with the manufacturers' instructions. If direct connected
to blower through a lubricated type coupling, the coupling
should be checked and greased each time blower oil is
changed. This will help reduce wear and prevent it from
causing vibration. In a belted drive system, check belt
tension periodically and inspect for frayed or cracked
belts. Refer to tensioning instructions under INSTALLA-
TION.
In a new and properly installed blower there are no
moving contacts between the two impellers, or between
the impellers and cylinder or headplates. Wear is then con-
fined to the bearings which support and locate the shafts,

)
the oil seals, and the timing gears. All are lubricated and
wear should be minimal if clean oil of the correct grade is
always used. Seals are
subject to deterioration as well as
wear, and may require replacement at varying periods.
Sealing rings are designed to operate with no rubbing
contact, once
temperature and thermal growth have
stabilized.
The rings, which are stationary, do rub the
rotating sleeves briefly during temperature cycles which
result from starting and stopping the blower. However,
the hardened sleeves and the sealing rings are treated
with a dry lubricant coating which provides initiallubrica-
tion during break-in wear.
If the sealing rings become excessively worn, greater
leakage from the vents will occur. Seal rings should be
replaced if
vent leakage becomes excessive, or if inspec-
tion at the time of blower disassembly shows more than
.010" (.25 mm) axial clearance between ring and groove.
Shaft bearings have been selected to have optimum
life under average conditions with proper lubrication.
They are critical in the service life of the blower. Gradual
bearing wear
may allow a shaft position to change slight-
ly, until rubbing develops between impeller and cylinder
headplate. This will cause
spot heating, which can be
detected
by feeling these surfaces. Sudden bearing failure
is usually more serious. Since
the shaft and impeller is no
longer supported and properly located, extensive general
damage to the blower casing and gears is likely to occur.
Oil seals should be considered expendableitems, to be
replaced whenever drainage from
the headplate vent cavi-
ty becomes excessive, or when the blower is disassembled
for any reason. Sealing effectiveness can vary con-
siderably from seal to seal, and is also affected to surpris-
ing degree by shaft smoothness and freedom from scrat-
ches under the seal lip. Because of these normal variables,
minor seal leakage should
not be considered as indicating
a need for replacement.
Timing gear wear, when correct lubrication is main-
tained, should be negligible over a period of years. Gear
teeth are cut to provide the correct amount of backlash,
and gears correctly mounted on the shafts will accom-
modate a normal amount of tooth wear without permit-
ting contact between lobes of the two impellers.
However, a high oil level will cause churning and ex-
cessive heating indicated by an unusually high
temperature at the bottom of the gear housing. Conse-
quent heating of the gears will result in loss of tooth
clearance or backlash, and rapid wear of the gear teeth
usually will develop. Continuation of this tooth wear will
eventually produce impeller contacts (knocking), and from
this point serious damage will be unavoidable if blower
operation is continued. A similar situation can be produc-
ed suddenly by gear tooth fracture, which is usually
brought on by sustained overloading or momentary shock
loads.
Operating problems may also develop from causes
other than internal parts failure. Operating clearances
within a blower are only a few thousandths of an inch.
This makes
it possible for impeller interferences or casing
rubs toresult from shifts in the blower mounting, or from
changes in piping support. Foreign materials sucked into
the blower will also cause trouble, which can only be cured
9
by disconnecting the piping and thoroughly cleaning the
blower interior.
If this type of trouble is experienced, and the blower
is found to be clean, try removing mounting strains.
Loosen blower
mounting bolts and reset the leveling and
drive alignment. Then tighten mounting again, and make
sure that all piping meets blower connections accurately
and squar~ly before reconnecting it.
A wide
range of causes for operating troubles are
covered in the TROUBLE SHOOTING CHECKLIST.
The remedies suggested there in some cases nee~ to be
performed by qualified mechanics with a good
background of general experience, using procedures
detailed in this manual. Major repairs generally are to be
considered beyond
the scope of maintenance, and should
be referred
to the nearest Distributor listed on the last
page.
Warranty failures should not berepaired at all, unless
specific approval
has been obtained through a Sales Office
before starting work. Unauthorized disassembly within
the warranty period may void the warranty.
When a blower is taken out of service it may require
internal protection against rusting or corrosion. The need
for such protection
must be a matter of judgment based
on existing conditions as well as length of downtime.
Under favorable conditions, protection will probably not
be needed if shutdown is not longer than a month. Under
atmospheric conditions producing rapid corrosion, the
blower should be protected immediately. See long term
storage suggestions on page 3.
It is recommended that major repairs, if needed, be
performed by a factory authorized distributor listed on
the last page. However, it is recognized that this may not
always be practical especially when a spare blower is not
available. If a blower is out of the warranty period,
mechanical
adjustments and parts replacement may be
undertaken locally at the owner's option and risk. It is
recommended that Factory Parts be used to insurefit and
suitability. The maintenance of a small stock of on-hand
spare parts can eliminate possible delays. When ordering
parts give Item Numbers and their work descriptions
from Figures 6 or 7
and Table 6. Also specify quantities
wanted, and the blower size and serial number from the
nameplate.
Repairs or adjustments are best performed by person-
nel with good mechanical experience and the ability to
follow the instructions in this manual. Someoperations in-
volve extra care and patience, and a degree of precision
work. This is especially true in timing impellers and in
handling bearings. Experience indicates that a high
percentage of bearing failures is caused by dirt con-
tamination before or during assembly. Therefore, the
work area should be cleaned before starting disassembly,
and new or re-usable parts protected during progress of
the work.
In the following outlines of repair procedures,
numbers shown in brackets ( ) correspond to the Item
Numbers used in assembly drawings, Figure 6 and 7 and
parts list, Table 6. It is recommended that the procedures
be
studied carefully and completely, with frequent
reference to the drawing, before starting work. This will

produce better efficiency through an understanding of
what work is to be done, and the order of doing it. Before
disassembly,
mark all parts so that they may be returned
to original locations or relative positions.
Requirements for special tools will depend on
the
work to be done. If impeller clearances are to be checked
or re-set, a
set of long feeler gauges will be needed. Work
involving removal of
the timing gears cannot be ac-
complished without a highpressure hydraulic pump and a
suitable hydraulic puller,
and heat must be used during
bearing
and sleeve installation.
Design of
the ReS blowers is basically simple, and
most repair operations are straightforward. For this
reason, the following procedures are intended mainly to
indicate a perferred order of work and to call out points to
be observed. Where special operations are ~equired, detail-
ed coverage is given.
DISASSEMBLY
OF GEAR END
1. Drain oil completely from the gearbox sump by remov-
ing plugs
(22) in bottom of the headplate (1).
2. Loosen all flange screws (23) in the gearbox and
remove all but two upper screws. Install two (one on
top, one on bottom)
short capscrews from the
headplate to the cylinder to keep the headplate in
place.
Bump the gearbox to break the joint if it cannot
be pulled free by hand, then remove the last two screws
and lift off the gearbox. Remove gasket (7).
BACKS --
"_-I--t--J- fRONT S
• •
Figure4 -Impeller Timing Viewed From Gear End
3. Removing gears: Be sure that each gear is marked for
return to the same shaft in the same angular position
and
that the gears have match marks for the teeth. For
this operation, the impellers shouldbe wedged as shown
in Figure 4. Remove the locknuts (31), slinger (46) and
gear mounting washers (30). The timing gears (4) have
two
Vii -13 holeR for pulling purposes. Use a puller of the
type shown in Figure 5. The two Vi
'·13 screws should be
turned into the gear full depth, but make sure the puller
is square
with the shaft. If a shouldered plug as shown
in Figure 5 is not used, the gear may spring away from
the shaftwhen
it releases. Stand to one side and provide
rags or cushioning
material under the gear.
10
Figure 5 - Gear Removal
4. Remove bearing clamp plates (54) by unscrewing'cap-
screws (32) and removing lockwashers (35). Group the
shims (10) and the wavy spring washers (29) with each
clamp plate
and tag for ease of reassembly.
5. Remove the headplate -remove all capscrews holding
the headplate to the cylinder. Insert jacking screws in-
to the four (4) threaded flange hole and turn them in
evenly. The headplate will separate from
the cylinder.
The lip seals
(27), and bearing outer race and rollers,
are removed
with the headplate and can be pressed out
later.
6. Remove the bearing inner race and sleeve (38) from the
shaft with the aid of a bearing puller by inserting the
puller jaws in the groove in the sleeve and applying the
jacking screw against the end of the shaft. Protect the
threaded hole and the end of the shaft with a small, flat
spacer between
the shaft and the puller.
7. Remove the sealing rings (28) by inserting a thin,
pointed tool
at the gap to lift one end over the other so
its springs free.
DISASSEMBLY
OF DRIVE END
1. Remove the sheave or coupling and key from the drive
shaft. File off
any burrs or sharp edges along the
keyway.
2. Drain oil by removing drain plugs (22).
3. Remove the flange screws (23). Tap the drive end cover
to loosen it, then slide it along the shaft carefully to
avoid damaging
the lip seal (33) on the drive shaft
keyway. Remove the gasket (7). Remove oil slinger cap-
screw (60), oil slinger (40) and lockwasher (36).
4. Remove bearing clamp plates (34) by unscrewing
capscrews
(32) and removing lockwashers (35). Keep
shim halves (10) together exactly as removed
by tag-
ging them with each clamping plate.
5. Remove the headplate -remove all capscrews holding
headplate to the cylinder.
Insert jacking screws into
the four threaded flange holes
and turn them in evenly.
The headplate will separate from
the cylinder. The lip
seals
(27), and bearing outer race and, rollers, are
removed with
the headplate and can be pressed out
later.
6. Remove the bearing inner race and sleeve (38 or 39)
from the shaft with the aid of a bearing puller by
inserting the puller jaws in the groove in the sleeve and